1. Field of the Invention
This invention relates generally to fasteners for securing panel-like members together and more particularly, it relates to a push-pin and grommet assembly in which the grommet is inserted and retained in a fitting hole in a supporting panel, such as a metal door panel of an automobile vehicle, and thereafter to receive the push-pin for mounting a mating panel having a throughhole, such as a decorative lining panel, to the door panel. The push-pin and grommet assembly is adapted to absorb variations in the relative positions of the supporting panel and the mating panel caused by thermal expansion and contraction due to temperature changes.
2. Description of the Prior Art
A state-of-the-art search directed to the subject matter of this application uncovered the following patents:
______________________________________ 3,964,364 4,762,437 4,176,428 4,893,978 4,238,446 4,981,405 4,240,323 5,011,356 4,716,633 ______________________________________
There is disclosed in U.S. Pat. No. 3,964,364 to L. Richard Poe issued on Jun. 22, 1976, an initially single-piece fastener for detachably securing a pair of perforated members 21 and 22. The fastener includes a grommet 1 and a stud 12. The grommet has a head 2 with an opening therethrough and a pair of spreadable stem elements 5. The stud is initially attached at one end integrally to the grommet within the opening and is arranged, when severed from the head, to move axially between the stem elements. Thereafter, the stud is rotatable relative to the grommet so as to lock or release the grommet with respect to the perforated members.
There is disclosed in U.S. Pat. No. 4,176,428 to Shigeru Kimura issued on Dec. 4, 1979, a fixing device formed of a male member 1 adapted to be fixed to a decorating panel 3 and a complimentary female member 2 adapted to be attached to a supporting panel 17. The male member is provided with a holding flange 8 and a main flange 9 for securing the decorating panel therebetween. The male member further includes a shaft 6 extending from the lower surface of the main flange and a terminal bulbous engaging portion 10. The female member is provided with a hollow barrel body 11 having a flange head 13 at the open end of the barrel and shoulder means 14 for retaining the barrel in the supporting panel. The female member further includes a plurality of raised axially extending ribs 20 defining first and second spherical cavities 15 and 16 in spaced-apart relation and adapted to engage the bulbous engaging portion 10 in two axially spaced positions.
In U.S. Pat. No. 4,716,633 to Leandre Rizo issued on Jan. 5, 1988, there is taught a device suitable for fixing panels comprised of a male part 11 and a female part 31. The male part has a mounting head 12 and an elongated body 16 extending between the mounting head and a retaining head 23. The retaining head has a retaining surface 24 directed towards the mounting head, a snap-fastener surface 25, and a retaining edge 27 defined by the intersection of the retaining surface with the snap-fastener surface. The female part has a receptacle 34 for receiving the body 16 of the male part and at least one circumferential sector 36 for retaining the retaining head 23 of the male part in the axial direction. The retaining edge 27 is adapted to penetrate the sector 36 to provide an axial retention opposing withdrawal of the male part from the receptacle 34 in the female part.
In U.S. Pat No. 4,893,978 to Francis G. Franco issued on Jan. 16, 1990, there is taught a twistlock fastener 10 formed of a base member 12 and a latching member 14. The base member has a mounting portion 16 and a socket portion 18 with a square-shaped internal bore 22. The latching member is formed with a head portion 34 and a shank portion 36. The shank portion has a cylindrical section 38 adjacent to the head portion and has a pair of resilient bifurcated leg elements 42, 44 integrally formed with the cylindrical section. Each of the leg elements have a radial surface to provide latching shoulders 50, 52 for retaining the shank portion 36 in the bore 22. In order to permit the latching member to be rotatable relative to the square-shaped bore 22 in the base member 12, there are provided four rounded corner edges 71-76 which extend lengthwise of the leg elements between the cylindrical section 38 and the latching shoulders 50, 52. In order to provide positive quarter-turn latching positions, a flat surface 76 and 78 is formed on the respective leg elements 42 and 44 and tapers inwardly from the respective shoulders 50, 52 to the juncture with the cylindrical section to define triangular sections 80, 82 for engagement with the four sidewalls 28 of the bore 22.
In U.S. Pat. No. 5,011,356 to Miguel C. Fernandez issued on Apr. 30, 1991, there is disclosed a quarter-turn fastener for securing together a plurality of overlapped panels which is comprised of an elongated body portion 1, a head 2 disposed on one end of the body portion for engaging the outer surface of the uppermost panel, and a pair of resiliently flexible fingers 8 disposed on an opposite end of the body portion. A pair of diametrically opposed inclined cam portions 7a are also provided on the body portion at a position axially between the opposite ends of the body portions so as to engage the outer surface of the lowermost panel. When the fastener is rotated 90.degree., the cam portions will force the lowermost panel to move upwardly toward the uppermost panel so as to compress and seal together the plurality of overlapped panels.
The remaining patents listed above but not specifically discussed are believed to be of only general interest and show the state of the art in fixing devices for securing together panel-like members.
However, none of the prior art uncovered in the search disclosed push-pin and grommet assembly of a unique construction like that of the present invention which is capable of absorbing variations in the relative positions of a supporting panel and a mating panel to be attached caused by thermal expansion and contraction. This is accomplished by a pair of diametrically opposed semicylindrical-shaped portions and an enlarged tip portion formed on the push-pin and by providing cylindrical-shaped mating grooves and a substantially U-shaped mating slot formed in the grommet for retaining freely floating the semicylindrical-shaped portions and the tip portion in the respective grooves and slot so as to permit lateral sliding engagement between the opposed outer wall surfaces on the short sides of the main portion of the grommet. As a result, the push-pin and grommet assembly after fixation in the supporting panel allows for thermal expansion and contraction of the mating panel due to changes in the ambient temperature causing variations in the relative lateral positions of the mating panel and the supporting panel.